Magnetic sensors using alkali metal vapor cells and/or laser light sources commonly have heater circuits to maintain the cells and lasers at desired temperatures. Heating elements of the heater circuits are frequently formed in a conductor layer to reduce fabrication costs of the magnetic sensors. Currents through the heater elements generate magnetic fields which interfere with operation of the magnetic sensors. Layouts with current supply lines adjacent to current return lines reduce the interfering magnetic fields to some extent, but still limit the sensitivities of the magnetic sensors.